What would you like to know?
We publish the measurement method, its accuracy data and its limits in full, because a tool that reports numbers about your baby should be able to show where those numbers come from.
How it works, and how well
The two pages that show our working — the exact measurement, and how closely it agrees with reference measurements a person reviewed.
- How we measure head shape
The full pipeline and the actual formulas: how a photo becomes a width-to-length ratio, why 0.80 is the target, and why the photo angle is load-bearing.
- How accurate it is
Agreement figures across 3,349 real photos, the known failure mode that accounts for most of the error, and the limits of what this study proves.
- What this tool cannot do
The boundaries, in plain terms — what a photo measurement can and can't tell you.
Using it well
Getting a photo that measures consistently, and reading the result.
- How to take the photo
Straight down, top of the head up, whole head in frame. Why each part of that matters for the measurement.
- What the scores mean
Proportion, Symmetry and Harmony explained — including why a very round head and a very long head both score below a middling one.
- Tracking over time
How to compare scans month to month so the trend means something, rather than reading one number on one day.
Background
Context for what you're looking at.
- Why every baby's head looks different
The ordinary things that layer together — resting habits, time on the back, being born, and plain individual variation.
- Everyday habits and how a head rests
Ordinary variety in a day — tummy time, carrying, where the interesting side of the room is.
For informational and entertainment purposes only. Consult a professional if you have health concerns.